This invention generally relates to the field of plastic injection molding but, more particularly, to complementary mold and article architectures that permit fabrication by one-shot processes.
Injection molding in plastic is a well-established mass production technique in which a heated plastic material, usually a thermoplastic, is first forced under pressure into a mold until the fluid plastic completely fills the internal cavity defined by the mold parts and is shaped thereby to provide the desired article geometry. Afterward with cooling, the plastic solidifies. Then, the mold is opened, and the article is ejected.
This technique is very economical for fabricating parts in quantity where the material properties of plastic will suffice for the particular application since the cost of the mold can be distributed over a large number of parts to reduce individual piecepart cost. In addition, more or less complex geometry can be handled, and production rates can be enhanced through the use of multicavity molds.
Despite the attractiveness of the plastic injection molding process, it has its limitations, like other processes. Among these appears to be the inability within the present state of the art to fabricate in only one-shot multicomponent articles having relative movement between components. As a result, the fabrication of such articles is relatively more expensive because of the additional costs associated with longer cycle times and post molding assembly operations.
There are a number of examples in the literature, however, which do illustrate some of the possibilities for two-shot molding processes. For example, in U.S. Pat. No. 3,961,770 to Wrasman, there is shown a plug valve comprising an inner plug that is formed first and afterward a housing formed around it.
U.S. Pat. No. 3,995,822 to Einhorn et al. and No. 2,577,350 to Morin likewise show similar two-shot approaches where a first part is molded and then a second molded over that to provide a final article in which both parts are moveable with respect to one another.
Consequently, it is a primary object of the present invention to provide article and mold architectures which permit the one-shot molding of articles having two or more parts that are relatively moveable with respect to one another.
It is another object of the present invention to provide a mold architecture by which swivel connectors can be easily injection molded of plastic in a one-shot process.
It is still another object of the present invention to provide a swivel connector that can be easily injection molded of plastic in a one-shot process.
Other objects of the invention will in part be obvious and will in part appear in the detailed description that follows.